MyBatisPlus-QueryWrapper多条件查询以及修改

文章目录

• MyBatisPlus-QueryWrapper多条件查询以及修改
• • gt、ge、lt、le、isNull、isNotNull
  • eq、ne
  • between、notBetween
  • allEq
  • like、notLike、likeLeft、likeRight
  • in、notIn、inSql、notinSql、exists、notExists
  • or、and
  • 嵌套 or、嵌套 and
  • orderBy、orderByDesc、orderByAsc
  • last
  • 指定要查询的列
  • set、setSql

    gt、ge、lt、le、isNull、isNotNull

    • 大于 >
    • 例: gt("age", 18) → age > 18
    • ge 大于等于 >=
    • 例: ge("age", 18) → age >= 18
    • lt 小于 <
    • 例: lt("age", 18) → age < 18
    • le 小于等于 <=
    • 例: le("age", 18) → age <= 18
    • isNUll 字段 IS NULL
    • 例: isNull("name") → name is null
    • isNotNull 字段 IS NOT NULL
    • 例: isNotNull("name") → name is not null

      @Test
      public void queryWrapperOne() {
          QueryWrapper queryWrapper = new QueryWrapper<>();
          queryWrapper.
                  isNull("name")
                  .ge("age", 23)
                  .isNotNull("email");
          // 逻辑删除
          int result = userMapper.delete(queryWrapper);
          System.out.println(result);
          // 最终的语句为：UPDATE user SET deleted=1 WHERE deleted=0 AND name IS NULL AND age >= ? AND email IS NOT NULL
      }
      

      

      ---

      eq、ne

      • eq 等于 =
      • 例: eq("name", "老王") → name = '老王'
      • ne 不等于 <>
      • 例: ne("name", "老王") → name <> '老王'

        @Test
        public void queryWrapperTwo() {
            QueryWrapper queryWrapper = new QueryWrapper<>();
            queryWrapper.eq("name", "BNTang");
            // selectOne：返回的是一条记录，当出现多条时会报错
            User user = userMapper.selectOne(queryWrapper);
            System.out.println(user);
        }
        

        

        ---

        between、notBetween

        • BETWEEN 值1 AND 值2
        • 例: between("age", 18, 30) → age between 18 and 30
        • NOT BETWEEN 值1 AND 值2
        • 例: notBetween("age", 18, 30) → age not between 18 and 30

          @Test
          public void queryWrapperThree() {
              QueryWrapper queryWrapper = new QueryWrapper<>();
              queryWrapper.between("age", 20, 30);
              Integer count = userMapper.selectCount(queryWrapper);
              System.out.println(count);
          }
          

          

          ---

          allEq

          • allEq 全部 eq(或个别 isNull)

            个别参数说明：

            params: key 为数据库字段名, value 为字段值

            如果想表示 null isNull，则在 value 取值的时候传入一个 null, 为 null 时调用 isNull 方法, 为false时则忽略value为null的，也就是不拼接 value 为 null 的查询条件字段

            • 例1: allEq({id:1,name:"老王",age:null})→id = 1 and name = '老王' and age is null
            • 例2: allEq({id:1,name:"老王",age:null}, false)→id = 1 and name = '老王'

              @Test
              public void queryWrapperFour() {
                  QueryWrapper queryWrapper = new QueryWrapper<>();
                  Map queryParamsMap = new HashMap<>();
                  queryParamsMap.put("id", 1373266771933462530L);
                  queryParamsMap.put("name", "BNTang");
                  queryParamsMap.put("age", 23);
                  queryWrapper.allEq(queryParamsMap);
                  List users = userMapper.selectList(queryWrapper);
                  users.forEach(System.out::println);
              }
              

              

              个别参数说明

              filter: 过滤函数, 是否允许字段传入比对条件中

              params 与 null、IsNull 同上

              • 例1: allEq((k,v) -> k.indexOf("a") >= 0, {id:1,name:"老王",age:null})→name = '老王' and age is null
              • 例2: allEq((k,v) -> k.indexOf("a") >= 0, {id:1,name:"老王",age:null}, false)→name = '老王'

                

                如上图可看到，只添加了一个 id 查询的条件因为我写的过滤条件为要包含 i 这个字符串，所以只有第一个 key, value 包含了所以就只添加了 id

                ---

                like、notLike、likeLeft、likeRight

                • LIKE ‘%值%’
                • 例: like("name", "王")→name like '%王%'
                • NOT LIKE ‘%值%’
                • 例: notLike("name", "王")→name not like '%王%'
                • LIKE ‘%值’
                • 例: likeLeft("name", "王")→name like '%王'
                • LIKE ‘值%’
                • 例: likeRight("name", "王")→name like '王%'

                  @Test
                  public void queryWrapperFive() {
                      QueryWrapper queryWrapper = new QueryWrapper<>();
                      queryWrapper
                              .notLike("name", "BNTang")
                              .likeRight("email", "zq");
                      // 返回值是Map列表
                      List> users = userMapper.selectMaps(queryWrapper);
                      users.forEach(System.out::println);
                  }
                  

                  

                  ---

                  in、notIn、inSql、notinSql、exists、notExists

                  • 字段 IN (value.get(0), value.get(1), …)
                  • 例: in("age",{1,2,3})→age in (1,2,3)
                  • 字段 NOT IN (value.get(0), value.get(1), …)
                  • 例: notIn("age",{1,2,3})→age not in (1,2,3)
                  • 字段 IN ( sql语句 )
                  • 例: inSql("age", "1,2,3,4,5,6")→age in (1,2,3,4,5,6)
                  • 例: inSql("id", "select id from table where id < 3")→id in (select id from table where id < 3)
                  • 字段 NOT IN ( sql语句 )
                  • 例: notInSql("age", "1,2,3,4,5,6")→age not in (1,2,3,4,5,6)
                  • 例: notInSql("id", "select id from table where id < 3")→id not in (select id from table where id < 3)
                  • 拼接 EXISTS ( sql语句 )
                  • 例: exists("select id from table where age = 1")→exists (select id from table where age = 1)
                  • 拼接 NOT EXISTS ( sql语句 )
                  • 例: notExists("select id from table where age = 1")→not exists (select id from table where age = 1)

                    @Test
                    public void queryWrapperSix() {
                        QueryWrapper queryWrapper = new QueryWrapper<>();
                        queryWrapper.in("id", 1, 2, 3);
                        queryWrapper.inSql("id", "select id from user where id < 3");
                        // 返回值是Object列表
                        List